diff --git a/src/engine_robust.cc b/src/engine_robust.cc
index 9db11bc96..ab33b0f0a 100644
--- a/src/engine_robust.cc
+++ b/src/engine_robust.cc
@@ -39,7 +39,6 @@ void AllReduceRobust::AllReduce(void *sendrecvbuf_,
                                 size_t count,
                                 ReduceFunction reducer) {
   bool recovered = RecoverExec(sendrecvbuf_, type_nbytes * count, 0, seq_counter);
-  //utils::LogPrintf("[%d] AllReduce recovered=%d\n", rank, recovered);
   // now we are free to remove the last result, if any
   if (resbuf.LastSeqNo() != -1 &&
       (resbuf.LastSeqNo() % result_buffer_round != rank % result_buffer_round)) {
@@ -442,14 +441,10 @@ AllReduceRobust::TryRecoverData(RecoverType role,
     // do not need to provide data or receive data, directly exit
     if (!req_data) return kSuccess;
   }
-  utils::LogPrintf("[%d] !!Need to pass data\n", rank);
   utils::Assert(recv_link >= 0 || role == kHaveData, "recv_link must be active");
   for (int i = 0; i < nlink; ++i) {
     links[i].ResetSize();
   }
-  if (role == kPassData) {
-    links[recv_link].InitBuffer(1, size, reduce_buffer_size);
-  }
   while (true) {
     bool finished = true;
     utils::SelectHelper selecter;
@@ -457,9 +452,12 @@ AllReduceRobust::TryRecoverData(RecoverType role,
       if (i == recv_link && links[i].size_read != size) {
         selecter.WatchRead(links[i].sock);
         finished = false;
-      }
+      }      
       if (req_in[i] && links[i].size_write != size) {
-        selecter.WatchWrite(links[i].sock);
+        if (role == kHaveData ||
+            (role == kPassData && links[recv_link].size_read != links[i].size_write)) {
+          selecter.WatchWrite(links[i].sock);
+        }
         finished = false;
       }
       selecter.WatchException(links[i].sock);
@@ -496,12 +494,12 @@ AllReduceRobust::TryRecoverData(RecoverType role,
         utils::Assert(min_write <= links[pid].size_read, "boundary check");
         if (!links[pid].ReadToRingBuffer(min_write)) return kSockError;    
       }
-      for (int i = 0; i < nlink; ++i) {
-        if (req_in[i] && selecter.CheckWrite(links[i].sock)) {
+      for (int i = 0; i < nlink; ++i) {        
+        if (req_in[i] && selecter.CheckWrite(links[i].sock) && links[pid].size_read != links[i].size_write) {
           size_t start = links[i].size_write % buffer_size;
           // send out data from ring buffer
-          size_t nwrite = std::min(buffer_size - start, links[pid].size_read - links[i].size_write);
-          ssize_t len = links[pid].sock.Send(links[pid].buffer_head + start, nwrite);
+          size_t nwrite = std::min(buffer_size - start, links[pid].size_read - links[i].size_write);          
+          ssize_t len = links[i].sock.Send(links[pid].buffer_head + start, nwrite);
           if (len != -1) {
             links[i].size_write += len;
           } else {
@@ -559,7 +557,6 @@ AllReduceRobust::TryGetResult(void *sendrecvbuf, size_t size, int seqno, bool re
   } else {
     role = kRequestData;
   }
-  utils::LogPrintf("[%d] role=%d\n", rank, role);
   int recv_link;
   std::vector<bool> req_in;
   ReturnType succ = TryDecideRouting(role, &size, &recv_link, &req_in);
@@ -590,7 +587,6 @@ bool AllReduceRobust::RecoverExec(void *buf, size_t size, int flag, int seqno) {
   }
   // request
   ActionSummary req(flag, seqno);  
-  utils::LogPrintf("[%d] propose flag=%d, seq=%d\n", rank, flag, seqno);  
   while (true) {
     // action
     ActionSummary act = req;    
diff --git a/test/test_recover.cpp b/test/test_recover.cpp
index 9267cdca5..215177f20 100644
--- a/test/test_recover.cpp
+++ b/test/test_recover.cpp
@@ -19,6 +19,7 @@ inline void TestMax(test::Mock &mock, size_t n, int ntrial) {
     ndata[i] = (i * (rank+1)) % 111;
   }
   mock.AllReduce<op::Max>(&ndata[0], ndata.size());  
+  if (ntrial == 0 && rank == 15) throw MockException();
   for (size_t i = 0; i < ndata.size(); ++i) {
     float rmax = (i * 1) % 111;
     for (int r = 0; r < nproc; ++r) {